Emergency officials in Southern California lifted evacuation orders on Monday for some residents near a damaged tank containing methyl methacrylate at the GKN Aerospace Transparency Systems plant in Garden Grove, after the tank's internal temperature dropped sufficiently to eliminate the risk of a catastrophic explosion.
Orange County Fire Authority division chief Craig Covey said during a news conference that there is no longer a risk of catastrophic explosion. Authorities detected no hazardous chemical levels as of Monday. The tank, which held 6,000 to 7,000 gallons of methyl methacrylate, overheated on Thursday, causing pressure buildup and prompting the evacuation of about 50,000 residents. A crack discovered on Sunday relieved some pressure, and the internal temperature fell to 93°F (33.9°C) on Monday, down from 100°F a day earlier.
Andrew Whelton, a Purdue University engineering professor who studies environmental contamination, cautioned that some risk of explosion remains while the chemical is still hot and reactive. He said temperatures need to fall closer to ambient levels (roughly 60–70°F) for conditions to be significantly safer. Whelton noted that pressure release likely released some chemical into the atmosphere, and detection depends on monitoring equipment placement. Orange County health officials stated the chemical is easy to smell and people may notice it over a large area without being harmed.
GKN Aerospace, a British company that supplies cockpit windows, canopies, and windshields for military and commercial aircraft, employs about 16,000 people across 32 manufacturing sites in 12 countries. In 2025, GKN Aerospace agreed to pay state regulators over $900,000 to settle violations involving recordkeeping, permitting issues, and nitrogen oxide emissions, according to the South Coast Air Quality Management District.
Kim Yen, a retiree living two blocks from the plant, expressed relief but said she wants to be sure it is safe before returning home. The evacuation zone was reduced, and some residents were allowed to return. GKN Aerospace technical specialists and the Orange County Fire Authority removed external insulation from the tank to help cool its contents.
Source: Read the original report | Published: May 25, 2026